1. Field of the Invention
The present invention relates to disk drives, and more particularly, to disk drives used in audiovisual recording systems.
2. Description of the Related Art
Existing video recording systems, such as systems which comprise a personal video recorder, permit users to view audiovisual programming as it is received in real time and to record in non-volatile memory the incoming audiovisual programming for later viewing. A typical system comprises a set-top box and a personal video recorder including a hard disk drive with an IDE (Integrated Drive Electronics) or SCSI (Small Computer System Interface) disk interface for transferring data to and from the hard disk drive. Both the hard disk drive and the personal video recorder electronics typically include cache or buffer memory to facilitate data transfer between the two.
The set-top box receives a plurality of programming channels from a multiple server operator (xe2x80x9cMSOxe2x80x9d), such as a cable television provider, and includes a tuner which can be used to select a program channel for viewing or recording. The output of the set-top box is typically transmitted to the personal video recorder via an audiovisual interface which includes an MPEG (Motion Picture Experts Group) encoder, or an encoder compatible with another compression standard. The encoder is used to generate digital-formatted, compressed audiovisual data for recording which can then be transferred to the hard disk drive across the disk interface. The process of encoding audiovisual data is typically performed using its own dedicated memory as a xe2x80x9cscratchpad.xe2x80x9d
The single disk interface is also used to play back the recorded audiovisual data by transferring it from the hard disk drive to a display device via an appropriate decoder. As with the process of encoding, the process of decoding is typically performed using a memory dedicated to the decoder.
Besides being used to transfer audiovisual data, the disk interface is also typically used to transfer non-audiovisual data to and from the hard disk drive for storage and retrieval, and to transmit data transfer commands to the hard disk drive. The incoming and outgoing audiovisual data, non-audiovisual data, and the data transfer commands each utilize a fraction of the available bandwidth of the disk interface.
One aspect of the present invention relates to a disk drive connectable to a host system that includes an audiovisual source, the disk drive comprising a disk, a buffer memory, and an audiovisual interface responsive to first data from the audiovisual source to provide audiovisual data. The disk drive further comprises a host command interface adapted to receive host commands from the host system. The disk drive further comprises a disk controller coupled to the audiovisual interface, the host command interface, the disk, and the buffer memory. The disk controller is responsive to the host commands to selectively allocate at least a portion of the buffer memory for the audiovisual data. The disk controller is further responsive to the host commands to selectively transfer the audiovisual data from the audiovisual interface to the buffer memory. The disk controller is further responsive to the host commands to selectively transfer the audiovisual data from the buffer memory to the disk to be stored.
Another aspect of the present invention relates to a disk drive connectable to a host system, the disk drive comprising a disk having audiovisual first data, a buffer memory, and an output interface. The disk drive further comprises a host command interface that receives host commands from the host system. The disk drive further comprises a disk controller coupled to the output interface, the host command interface, the disk, and the buffer memory. The disk controller is responsive to the host commands to selectively allocate at least a portion of the buffer memory for retrieved audiovisual data. The disk controller is further responsive to selectively transfer the audiovisual first data from the disk to the buffer memory as the retrieved audiovisual first data. The disk controller is further responsive to selectively transfer the retrieved audiovisual data from the buffer memory to the output interface.
Another aspect of the present invention relates to a method of storing and retrieving audiovisual data utilizing a disk drive. The method comprises receiving host commands from a host system at a host command interface. The method further comprises selectively allocating at least a portion of a buffer memory for audiovisual data. The method further comprises receiving first data from the host system at an audiovisual interface. The method further comprises providing digital-formatted audiovisual data in response to the first data. The method further comprises selectively transferring the audiovisual data to the buffer memory in response to the host commands. The method further comprises selectively transferring the audiovisual data from the buffer memory to a disk in response to host commands. The method further comprises selectively allocating at least a second portion of the buffer memory for retrieved audiovisual data. The method further comprises selectively transferring the audiovisual data from the disk to the buffer memory as the retrieved audiovisual data in response to the host commands. The method further comprises selectively transferring the retrieved audiovisual data from the buffer memory to an output interface.